Rethinking Automated Bed Leveling For 3D Printers

Automatic bed leveling is the next killer feature that will be found on all commercial filament printers. It’s a problem that has been solved a few dozen times already; there are just so many ways you can go about it. The Printrbot uses an inductive sensor to determine the position of the metal bed in relation to the nozzle. The Lulzbot Mini touches the nozzle itself to four contacts on the corner of the bed. There are even a few projects that will mechanically level the bed with the help of a system of cams and springs. It’s a difficult problem, and none of these solutions are perfect. [mjrice] has been thinking about the problem, and he hit upon a solution that is simple, elegant, and can be replicated on a 3D printer. It’s the RepRap solution to 3D printing, and it looks cool, to boot.

Instead of using the nozzle as a contact, getting an inductive sensor, or fabricating a baroque system of gears and cams, [mjrice] is doing this the old-fashioned way: a simple microswitch, the same type of switch you would find on the limit switches of any RepRap. Having a switch at the same Z position as a nozzle is an iffy idea, so [mjrice] made this switch retract into the extruder during printing, without using any motors, servos, or other electromechanical contrivances.

The key to this setup is a simple spring and a rack gear. When this rack gear is hit from the left side, it moves an arm and places the switch down on the bed. Hit the rack from the right side, and the switch folds up into the extruder. Combine this with a bit of G-code at the beginning of the print, and the switch will move down, figure out the actual height of the bed, and flip up out of the way. Beautiful, elegant, and the algorithms for bed leveling are already in most major printer firmwares.

You can check out the video of the mechanism below. It’s a great little device, and since it’s on a RepRap first, it’s not going to show up in a proprietary 3D printer next.

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Ask Hackaday: Selling CAD Prints That Are Not Yours

[Louise] tried out her new E3D Cyclops dual extrusion system by printing a superb model dragon. The piece was sculpted in Blender, stands 13cm tall and can be made without supports. It’s an impressive piece of artwork that reflects the maker’s skill, dedication and hard work. She shared her creation on the popular Thingiverse website which allows others to download the file for use on their own 3D printer. You can imagine her surprise when she stumbled upon her work being sold on eBay.

It turns out that the owner of the eBay store is not just selling [Louise]’s work, he’s selling thousands of other models taken from the Thingiverse site. This sketchy and highly unethical business model has not gone unnoticed, and several people have launched complaints to both Thingiverse and eBay. Now, there are lots of things to talk about here, but the 800 pound high voltage transformer in the room is the legality of the whole thing. What he’s doing might be unethical, but is it illegal?

When [Louise] politely asked the eBay store owner to remove her work, he responded with:

“When you uploaded your items onto Thingiverse for mass distribution, you lost all rights to them whatsoever. They entered what is known in the legal world as “public domain”. The single exception to public domain rules are original works of art. No court in the USA has yet ruled a CAD model an original work or art.”

Most of the uploaded CAD models on Thingiverse are done under the Creative Commons license, which is pretty clear in its assertion that anyone can profit from the work. This would seem to put the eBay store owner in the clear for selling the work, but it should be noted that he’s not properly attributing the work to the original creator. There are other derivatives of the license, some of which prohibit commercial use of the work. In these cases, the eBay store owner would seem to be involved in an obvious violation of the license.

There are also questions stirring with his use of images.  He’s not taking the CAD model and making his own prints for images. He lifting the images of the prints from the Thingiverse site along with the CAD files. It’s a literal copy/paste business model.

With that said,  the eBay store owner makes a fairly solid argument in the comments section of the post that broke the news. Search for the poster named “JPL” and the giant brick of text to read it. He argues that the Thingiverse non-commercial license is just lip service and has no legal authority. One example of this is how they often provide links to companies that will print a CAD design on the same page of a design that’s marked as non-commercial. He sums up one of many good points with the quote below:

“While we could list several other ways Thingiverse makes (money), any creator should get the picture by now-Thingiverse exists to make Stratasys (money) off of creators’ designs in direct violation of its very own “non-commercial” license. If a creator is OK with a billion-dollar Israeli company monetizing his/her designs, but hates on a Philly startup trying to make ends-meet, then they have a very strange position indeed.”

OK Hackaday readers, you have heard both sides of the issue. Here’s the question(s):

1.  Is the eBay seller involved in illegal activity?

2. Can he change his approach to stay within the limits of the license? For instance, what if he credits the                      original maker on the sale page?

3. How would you feel if you found your CAD file for sale on his eBay store?

Good Vibrations in 3D-Printed Clay

An engineer with a 3D printer wants everything to be rigid and precise. Wobble induced by flex in the z-axis feedscrews, for instance, makes telltale wavy patterns in the surface that match exactly the screw pitch. Nobody likes those, right? Certainly not an engineer!

good_vibrations-shot0008_thumbnailBut one man’s surface irregularity is another man’s ornamentation. The details we have are sparse, but from looking at the video (also inlined below the break) it’s clear enough: [Olivier van Herpt] and [Ricky van Broekhoven] stuck a vibrating woofer underneath the print bed of their ceramic printer, and use it to intentionally ruin their smooth surface. And they do so to great artistic effect!

We’re not suggesting that you give up entirely on your calibrations, but we do appreciate a little out-of-the-box thinking from time to time. But then our internal engineer raises his head and we wonder if they’re linking the pitch of the woofer to the feed rate of the print head. Your thoughts in the comments?

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The OpenR/C Project

The Open RC Truggy that started it all.
The Open RC Truggy that started it all.

[Daniel Norée] started the OpenR/C project back in 2012 when he bought a Thing-O-Matic. In search of a project to test out his new printer, he set his sights on a remote controlled car, which as he put it,”… seemed like the perfect candidate, as it presents a lot of challenges with somewhat intricate moving parts along with the need for a certain level of precision and durability.

After releasing his second design, the OpenR/C Truggy, he realized a community was forming around this idea, and needed a place to communicate. So, he created a Google+ group. Today, the Truggy has been downloaded over 100,000 times and the Google group has over 5,000 members. It’s a very active community of RC and 3d printing enthusiasts who are testing the limits of what a 3d printer can do.

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Super Sizing the Printrbot Metal Simple

The Printrbot Simple Metal is a good 3D printer, with a few qualifications. More accurately, the Printrbot Simple Metal is a good first 3D printer. It’s robust, takes a beating, can produce high-quality prints, and is a great introduction to 3D printing for just $600. There are limitations to the Printbot Simple Metal, the most important is the relatively small 150mm cubed build volume.

[ken.do] wanted to print large parts, specifically scale aircraft wings and panels. While the Printrbot can’t handle these things normally, the design of the printer does lend itself to increasing the size of the build volume to 500mm long and 500mm high.

Increasing the build height on the Printrbot is as simple as adding two longer smooth rods and a single threaded rod to the Z axis. Increasing the X axis is a bit trickier: it requires a very flat sheet that doesn’t warp or bend over 500 mm, even when it’s being supported in different places. [ken.do] is engineering stiffness into a build plate here. The solution to a huge bed is a two kilogram aluminum bed supported by heavier rails and riding on a massive printed bushing block. Does it work? Sure does.

If you want to print tall objects, the current crop of 3D printers has you covered: just get a delta, and you’re limited only by the length of the extrusion used in the body. Creating big objects in all three dimensions is a marginally solved problem – just get a big printer. Big printers have drawbacks, notably the incredible power requirements for a huge heated build plate.

The ability to print long objects is a problem that’s usually not addressed with either commercial 3D printers or RepRaps. We’re glad to see someone has finally realized the limitations of the current crop of 3D printers and has come up with a way to turn a very good first printer into something that solves a problem not covered by other 3D printers.

Repairing a MakerBot Mightyboard Clone

It can be argued that MakerBot, a company that makes popular 3D printers, hit its pinnacle with the introduction of the Replicator 2. It was designed well and completely open source, including the motherboard that drove the printer – known as the Mightyboard. China quickly picked up on the success of the Replicator 2 and copy/pasted several of their own versions (at a much cheaper sale price). One of these outfits is called Wanhao, and their version of the Replicator 2 is called..wait for it…the Duplicator!

Their version of the Mighyboard is identical to the original, minus a few nickle and dime components. This suggests that Wanhao made an effort to cut as much cost as possible without looking at what functionality they were removing. And anytime a company does this, you can bet the quality of the board manufacturer is at the bottom of the barrel.   [Avrydev] found this out the hard way when he repaired a faulty motherboard from a broken Duplicator.

The board would not connect to the software via USB, and the startup tune pitch was off. [Arvydev] flashed new firmware via ICSP, but that did not help. He eventually clued in on the main crystal for the Atmega processor. A quick swap and presto! The printer is as good as new.

Solder Stencils with a 3D Printer

If you are soldering with paste, a stencil makes life a lot easier. Sure, you can apply paste by hand with a syringe, but a modern PCB might have hundreds or even thousands of pads. Like a lot of us, [Robert Kirberich] doesn’t like paying to have stencils made and he wondered if he could use his 3D printer to make stencils. He found the answer was yes.

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